a = {"zero": 0, "one": 1, "two": 2, "three": 3, 'four': 4, "five": 5, "six": 6, "seven": 7, "eight": 8, "nine": 9}
lis = [101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239,
       241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433,
       439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641,
       643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863,
       877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997
         ]
num = input().split()
num2 = ""
result = []
fl = True
for i in num:
    if i not in a.keys():
        fl = False
        break
    else:
        num2 += str(a[i])

if fl is False or len(num2):
    print("Wrong input")
else:
    for i in range(int(num2) - 1, 101, -1):
        if i in lis:
            result.append(i)
            break
    for i in range(int(num2) + 1, 999):
        if i in lis:
            result.append(i)
            break
    result = sorted(result)
    t = min(list(map(lambda x: abs(x - int(num2)), result)))
    for i in result:
        if abs(i - int(num2)) == t:
            print(i)
            break
